Manufacturing apparatuses for semiconductor devices, flat display panels, and various other electronic devices are normally made of stainless steel. However, in the case of, for example, an apparatus which is adapted to process a large substrate (2.88 m×3.08 m) for manufacturing a large display, since its weight becomes too heavy, it has been studied to use a lightweight metal, for example, an Al alloy. However, in the case of the manufacturing apparatus for such a large substrate, the Al alloy is deformed by its own weight so that an O-ring or the like for maintaining the airtightness does not work. In view of this, an Al alloy which is excellent in strength has been required.
On the other hand, since the inside of manufacturing apparatuses for various electronic devices is exposed to corrosive chemical solutions, corrosive gases, plasmas, and so on, even if the manufacturing apparatus is made of an Al alloy, its inside should be coated with a strong passive protective film. In view of this, an Al alloy which is excellent in strength and whose surface can be coated with a strong passive protective film has been particularly required.
As an Al alloy which can increase the mechanical strength and whose surface can be coated with a strong passive protective film, one shown in Patent Document 1 (JP-A-H9-176772) is known, for example. However, the material disclosed in Patent Document 1 is insufficient in strength for application to recent large-scale manufacturing apparatuses and, further, a passive fluoride film disclosed in Patent Document 1 is insufficient against various corrosive gases • plasmas.
The present inventors have proposed using an Al alloy added with Mg and Zr and anodizing its surface in a non-aqueous solution, thereby obtaining a passive protective film (Patent Document 2: International Publication WO2006/134737 Pamphlet). However, the material disclosed in Patent Document 2 is insufficient in strength for application to recent large-scale manufacturing apparatuses and, further, the anodic oxide film disclosed in Patent Document 2 is also insufficient in corrosion resistance to a chlorine gas.
Patent Document 3 (JP-A-H1-272739) describes a coloring aluminum alloy added with/containing coloring elements, but there is no disclosure of obtaining a high-hardness member with a Vickers hardness greater than 30, which is made of a high-purity Al alloy added with/containing only elements adapted to increase the hardness of the aluminum alloy, i.e. with extremely low contents of unavoidable impurities. An aluminum alloy of sample No. 8 in Table 1 shown as an Example in Patent Document 3 (JP-A-H1-272739) contains not only Ce, Mg, and Zr, but also 4.90 wt % Zn as coloring elements.